Preparation method and application of catalyst for indirectly electro-catalyzing decomposition of hydrogen sulfide

Abstract

The invention belongs to the field of petrochemical engineering, and particularly relates to a preparation method and application of a catalyst for indirectly electro-catalyzing decomposition of hydrogen sulfide. The method is characterized in that electrochemical devices are combined to form an indirect electro-catalysis hydrogen sulfide decomposition process, nickel-doped molybdenum carbide (Ni and Mo2C) is used as a catalyst, electro-catalysis reaction is operated for 8 hours by adopting a one-pot method under the conditions of room temperature, normal pressure and 2V, hydrogen sulfide is decomposed into sulfur and hydrogen, the sulfur is recovered by adjusting the pH value, and hydrogen and sulfur products are obtained at the same time. The process can be used for efficiently and indirectly electrocatalyzing hydrogen sulfide to obtain sulfur and hydrogen under the mild conditions of room temperature, normal pressure and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method and application of a catalyst for indirect electrocatalytic decomposition of hydrogen sulfide, and belongs to the field of petroleum and chemical industry. The present application provides a new synthesis method for the decomposition of hydrogen sulfide into sulfur and hydrogen by using a simple, economical and recyclable catalyst for electrocatalytic operation (room temperature and normal pressure). The international patent classification is C17 / 16. TECHNICAL BACKGROUND

[0002] In the process of petroleum processing, sulfur compounds are converted into hydrogen sulfide (H2S) and widely exist in raw natural gas. H2S has strong corrosive and toxic properties, that is, it shows strong toxicity at a low concentration (50 ppm), and the oxidation of H2S into sulfur dioxide in the air can pollute water, air and soil and form sulfuric acid in water, so it is very important to treat H2S. In addition, H2S is a potential valuable chemical rich in elements H and S. Therefore, the technical innovation of decomposing H2S to produce clean energy hydrogen (H2) and form a high value-added product-sulfur has attracted much attention.

[0003] So far, the main methods for directly decomposing H2S include: (1) traditionally, H2S is separated and removed after adsorption and oxidation processes. For example, methyldiethanolamine (MDEA) is a mainstream H2S drying agent in natural gas purification processes, which has excellent selectivity and stability; (2) the Claus process is used in industry to produce elemental sulfur; (3) the hydrogen sulfide methane reforming (H2SMR) method can effectively produce H2 for commercial-scale implementation. The first method has a relatively high production cost, especially a large amount of solid waste generated during the production process, which is difficult to treat and has a high treatment cost, and does not meet the requirements of green production. The limitation of the second method is that the Clause process can only recover elemental sulfur, and H2 is completely converted into H2O, and must be operated at a high temperature of 1000-1200℃, H + becomes water, and this process has problems such as high energy consumption and no H2 production. The main disadvantage of CH4 conversion in the third method is that there is more CO2 directly and indirectly discharged: for a certain mole of CH4, the reaction directly discharges one mole of CO2. The method of electrolysis can efficiently decompose H2S into H2 and sulfur, and the electrochemical decomposition of H2S is represented by two half-reactions:

[0004] H2S→2H + +2e - +S(anode) (1)

[0005] 2H + +2e - →H2 (catode) (2)

[0006] The following half-reactions occur during direct electrolysis of H2S: sulfide oxidation reaction (SOR) at the anode (Equation 1) and hydrogen evolution reaction (HER) at the cathode (Equation 2). This method has lower energy consumption, and in addition to H2 (green fuel), the generated sulfur after electrolysis can also be used as a cathode material for sulfur-based batteries, thereby achieving a circular economy. However, elemental sulfur generated during anodic SOR usually leads to sulfur passivation, hindering the reaction activity and posing a significant obstacle to the promotion of H2S decomposition by electrolysis. To address the problem of sulfur passivation in direct electrocatalysis, many efficient electrocatalysts have been developed in recent years to promote SOR, including mixed metal oxides (MMO), carbon-based catalysts, platinum, metal sulfides, and alloy catalysts. Research on efficient, simple, and easy-to-synthesize catalysts has become a research focus. However, due to the direct conversion of sulfide to sulfur, catalyst etching and the accumulation of non-conductive sulfur on the electrode surface hinder the further decomposition of H2S by the catalyst, leading to a sharp decline in activity.

[0007] In indirect electrocatalysis, compared to direct electrolysis, the formation of sulfur accumulation on the catalyst surface is prevented by vigorous stirring of the solution and catalyst, which can avoid the overpotential of electron transfer and alleviate sulfur passivation. Molybdenum carbide complex (Mo2C) has a similar d-band electronic structure to Pt and is a promising electrocatalyst to replace expensive noble metal catalysts. In particular, Mo2C is considered a highly efficient electrocatalyst due to its most stable lattice structure and high electronic efficiency, but its actual catalytic activity and electrochemical stability are still lower than those of noble metal electrocatalysts. Element doping has been proven to be an effective method to improve the electronic structure of materials, such as the doping of Ni, Co, Cu, N, and P atoms, which can change the electronic structure of MoC x The electronic structure of the material, improve the catalytic activity, engineering particle size, morphology and crystal phase. In particular, the doping of Ni in Mo2C can promote the process of electrolysis of H2S, but the carbon source of Mo2C is mostly carbon-containing gas (such as CH4, C2H6, CO2, CO, and C7H8 atmosphere), and the synthesis process is complex and dangerous. Using organic ligands as a carbon source to prepare Ni@Mo2C does not require carbon-containing gas, has the characteristics of simple steps, uniform distribution of Ni-Mo at the atomic scale, and close interaction. So far, the application of Ni@Mo2C as an indirect electrocatalyst for efficient indirect electrocatalytic decomposition of H2S into H2 and sulfur is still rare and challenging.

[0008] Therefore, in order to solve the problems of low mass transfer efficiency, difficult catalyst recovery and complicated operation procedure, the present application provides a preparation method for indirectly electrocatalytic decomposition of H2S into sulfur and H2 in the presence of a Ni@Mo2C catalyst. An electrochemical device is combined to form an indirect electrocatalytic hydrogen sulfide decomposition process, and a nickel-doped molybdenum carbide (Ni@Mo2C) is used as a catalyst. Under the conditions of room temperature, normal pressure and 2V, the electrocatalytic reaction is carried out by a "one-pot" method for 8h, and H2S is decomposed into sulfur and H2. The sulfur is recovered by filtration, and H2 and sulfur products are obtained. The process can efficiently indirectly electrocatalyze H2S into sulfur and H2 under the conditions of room temperature, normal pressure and isothermal conditions. SUMMARY

[0009] The present application is a simple, economical and recyclable Ni@Mo2C indirect electrocatalyst "one-pot" method (room temperature, normal pressure) for electrocatalytic decomposition of H2S into S and H2. The method has the advantages of easy operation, high yield, recyclable catalyst, non-toxic and non-polluting.

[0010] The present application is a preparation method for indirectly electrocatalytic decomposition of H2S into S and H2 in the presence of a Ni@Mo2C indirect electrocatalyst, characterized by:

[0011] A catalyst preparation method and application for indirectly electrocatalytic decomposition of hydrogen sulfide:

[0012] (1) Preparation of indirect electrocatalyst;

[0013] (2) Introducing hydrogen sulfide into the electrolyte;

[0014] (3) Electrolyzing the electrolyte containing hydrogen sulfide;

[0015] (4) Filtering and recovering the catalyst;

[0016] (5) Adjusting the pH value of the solution and storing it in an ice bath to recover the light yellow sulfur precipitate;

[0017] (6) Washing the catalyst with water and ethanol to obtain the sulfur product.

[0018] The present application has unique advantages. The new method for indirectly electrocatalytic decomposition of H2S into sulfur and H2 is simple, economical, environmentally friendly, and has a low catalyst price and high yield. BRIEF DESCRIPTION OF DRAWINGS Figure 1 The catalyst preparation flowchart. Figure 2 The process flowchart for indirectly electrocatalytic decomposition of hydrogen sulfide.

[0019] EFFECT

[0020] A new method for indirect electrocatalytic decomposition of H2S into elemental sulfur and H2 based on the presence of Ni@Mo2C catalyst is studied in this paper, which can effectively decompose H2S into valuable H2 and elemental sulfur. In this system, Ni@Mo2C as an indirect electrocatalyst shows excellent electrocatalytic efficiency, with H2S removal rate up to 99%, elemental sulfur product yield up to 95%, and H2 generation. This work may open up a new way for electrocatalytic H2S decomposition in indirect electrocatalytic systems to produce high-value elemental sulfur and H2 by exploring metal-doped molybdenum carbide complex materials.

[0021] CLAIM

[0022] 1. A method for preparing and using a catalyst for indirect electrocatalytic decomposition of hydrogen sulfide, characterized by: (1) preparation of an indirect electrocatalyst; (2) introduction of hydrogen sulfide into an electrolyte; (3) electrolysis of the electrolyte containing hydrogen sulfide; (4) filtration and recovery of the catalyst; (5) adjustment of the solution pH and storage in an ice bath to recover the light yellow elemental sulfur precipitate; (6) washing of the catalyst with water and ethanol to obtain the elemental sulfur product.

[0023] 2. The method of claim 1, wherein a Ni@Mo2C catalyst is prepared by the following steps: slowly adding an ethanol solution of trimesic acid to a H2O solution of molybdic acid, mixing to form a precipitate, continuing to stir, filtering the precipitate, washing the precipitate with ethanol, and drying overnight to obtain HK-Mo; placing the HK-Mo in a porcelain boat and calcining under nitrogen protection at high temperature to obtain a PA-Mo molybdenum carbide catalyst; dissolving a certain amount of nickel nitrate in an aqueous solution, then adding the prepared PA-Mo molybdenum carbide and stirring for a certain time, then rotary evaporating with a rotary evaporator, drying overnight, and then calcining in a tube furnace under nitrogen protection to obtain the black precipitate of Ni@Mo2C catalyst.

[0024] 3. The method of claim 1, wherein a nickel foam is used as the working electrode (WE) and a carbon cloth is used as the counter electrode (CE); NaOH solution and Ni@Mo2C catalyst are added to the electrolytic cell, H2S gas is introduced into the electrolytic cell, and hydrogen and elemental sulfur are generated by electrolysis at a certain voltage; and the solution pH is adjusted to obtain elemental sulfur after the reaction is complete.

[0025] 4. The method of claim 1, wherein, to further separate the elemental sulfur, the deep yellow polysulfide solution is adjusted to a pH of 1-3 to precipitate, the solution is stored in an ice bath, and the light yellow elemental sulfur precipitate is collected to obtain the elemental sulfur product.

[0026] 5. The preparation method according to claim 2, characterized in that the mass ratio of the trimesic acid, molybdic acid and nickel nitrate is 0.5-2:1-5:0.2-1. DETAILED DESCRIPTION

[0027] The application will be described in detail below with reference to examples, but the scope of protection is not limited thereby.

[0028] The preparation method of the Ni@Mo2C indirect electrocatalyst is as follows:

[0029] First, the Ni@Mo2C catalyst is prepared. The ethanol solution (50 mL) of trimesic acid (1 g) is slowly added to the water (50 mL) solution of molybdic acid (2.5 g). After mixing, a precipitate is formed. The stirring is continued for 2 h. The precipitate is filtered. The precipitate is washed with ethanol and dried at 60℃ overnight, which is recorded as HK-Mo. The HK-Mo is placed in a porcelain boat and calcined under the condition of nitrogen protection. The temperature is raised to 800℃ at a rate of 5℃ / min and maintained for 3 h. The PA-Mo molybdenum carbide catalyst is obtained. A certain amount (0.2-0.5 g) of nickel nitrate is dissolved in an aqueous solution. Then the above prepared (1-2.5 g) PA-Mo molybdenum carbide is added and stirred for a certain time. Then the rotary evaporation instrument is used for rotary evaporation at 50℃. After rotary evaporation, it is placed in a drying box for drying at 60℃. After drying for 12 h, it is placed in a tube furnace under the condition of nitrogen protection. The temperature is raised to 800℃ at a rate of 5℃ / min and maintained for 3 h for carbonization. The obtained black precipitate is filtered out and dried to obtain the Ni@Mo2C catalyst.

[0030] The indirect electrocatalytic decomposition of H2S into sulfur and H2 in the presence of the Ni@Mo2C catalyst is as follows:

[0031] The electrochemical workstation is used for the reaction. The nickel foam is used as the working electrode (WE) and the carbon cloth is used as the counter electrode (CE). Under normal temperature and pressure, 100 mL of a sealed glass bottle is used. 1M NaOH solution (50 mL) and 40 mg of Ni@Mo2C catalyst are added to the reaction bottle. 2% H2S gas (100 ml / min) is introduced for 1 h. The electrocatalytic reaction is carried out at room temperature at a speed of 400 rpm under a constant voltage of 2V for 8 h. The hydrogen production is detected by gas chromatography. The yield is 10%-99%. Then 2% H2S gas (100 ml / min) is continuously introduced for 1 h. The above steps are repeated for 3 times. The solution pH is adjusted to 1-3 to precipitate. The solution is stored in an ice bath for 12 h. Then the yellowish sulfur precipitate is collected, washed with water and ethanol, dried at 60℃, and analyzed by P-XRD. The H2S conversion rate is about 65-99% and the sulfur yield is 58-95%. The Ni@Mo2C electrocatalyst after the reaction is dried and can be used for the next cycle experiment of the decomposition of H2S into S and H2.

[0032] The main content of the method is as follows:

[0033] (1) Selection of catalyst ratio:

[0034] First of all, the selection of raw material ratio for the synthesis of the catalyst is very important. After repeated experiments, we selected the catalyst Ni@Mo2C, with the following ratio conditions: the weight ratio of trimesic acid, molybdic acid, and nickel nitrate is 0.5-2:1-5:0.2~1.

[0035] (2) Study of reaction conditions:

[0036] How to improve the reaction efficiency, reduce energy waste and protect the environment is one of the key research contents. Therefore, under the condition of not using additional oxidizing agent, the method of electrocatalysis is adopted to reduce energy waste and protect the environment, and to achieve high yield. The reaction is carried out at normal pressure and room temperature, and the conversion rate of H2S is about 30-99%, and the yield of sulfur is about 24-95%.

[0037] Example 1:

[0038] Preparation of Ni@Mo2C catalyst: slowly add the ethanol solution (50 mL) of trimesic acid (1 g) to the water (50 mL) solution of molybdic acid (2.5 g). After mixing, a precipitate appears, continue to stir for 2 h. After washing with ethanol, the precipitate is dried at 60°C overnight. Record as HK-Mo. Put HK-Mo into a porcelain boat and calcine under nitrogen protection conditions, heat to 800°C at a heating rate of 5(°) / min and keep for 3h, to obtain PA-Mo carbonized molybdenum catalyst. Take a certain amount of 0.3g nickel nitrate dissolved in aqueous solution, then add 1.5g of the above PA-Mo carbonized molybdenum and stir. Then perform rotary evaporation at 50°C, and after rotary evaporation, place it in a drying box at 60°C for drying. After drying for 12h, put it into a tube furnace and carbonize under nitrogen protection conditions, heat to 800°C at a heating rate of 5(°) / min and keep for 3h. Filter out the black precipitate obtained, dry it, and obtain the Ni@Mo2C catalyst.

[0039] The reaction was performed using an electrochemical workstation with nickel foam as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and pressure, a 100-mL sealed glass bottle was charged with 1M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst. 2% H2S gas (100 mL / min) was introduced for 1 hour. The electrocatalytic reaction was carried out at room temperature at a rate of 400 rpm and a constant voltage of 2 V for 8 hours. The hydrogen production was measured by gas chromatography, yielding 99%. 2% H2S gas (100 mL / min) was then introduced for 1 hour, repeated three times. The solution pH was adjusted to 2, resulting in precipitation. The solution was then stored in an ice bath for 12 hours. The pale yellow sulfur precipitate was then collected, washed with water and ethanol, dried at 60°C, and analyzed by P-XRD, yielding a sulfur yield of 95%.

[0040] Example 2:

[0041] Preparation of the Ni@Mo2C catalyst: A solution of 0.5 g of mesitylene tribenzoic acid in 50 mL of ethanol was slowly added to a solution of 2.5 g of molybdic acid in 50 mL of water. A precipitate formed after mixing, and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60°C overnight. This was designated HK-Mo. HK-Mo was placed in a porcelain boat and calcined under nitrogen at a heating rate of 5°C / min to 800°C and held for 3 h, yielding the PA-Mo molybdenum carbide catalyst. A certain amount of 0.3 g of nickel nitrate was dissolved in the aqueous solution, followed by the addition of 1.5 g of the PA-Mo molybdenum carbide and stirring. The mixture was then rotary evaporated at 50°C and dried in a desiccator at 60°C for 12 h. After drying, the mixture was carbonized in a tube furnace under nitrogen at a heating rate of 5°C / min to 800°C and held for 3 h. The resulting black precipitate was filtered and dried to yield the Ni@Mo2C catalyst.

[0042] The reaction was performed using an electrochemical workstation with nickel foam as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and pressure, a 100-mL sealed glass bottle was charged with 1M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst. 2% H2S gas (100 mL / min) was introduced for 1 hour. The electrocatalytic reaction was carried out at room temperature at a rate of 400 rpm and a constant voltage of 2 V for 8 hours. The hydrogen production was measured by gas chromatography, yielding 92%. 2% H2S gas (100 mL / min) was then introduced for 1 hour, repeated three times. The solution pH was adjusted to 2, resulting in precipitation. The solution was then stored in an ice bath for 12 hours. The pale yellow sulfur precipitate was then collected, washed with water and ethanol, dried at 60°C, and analyzed by P-XRD, yielding an 85% sulfur yield.

[0043] Example 3:

[0044] Preparation of Ni@Mo2C catalyst: A solution of trimesic acid (2 g) in ethanol (50 mL) was slowly added to a solution of molybdic acid (2.5 g) in water (50 mL). A precipitate appeared upon mixing and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60 °C overnight. This is denoted as HK-Mo. HK-Mo was placed in a porcelain boat and calcined under nitrogen at a ramp rate of 5(°) / min to 800 °C and held for 3 h to obtain the PA-Mo molybdenum carbide catalyst. An amount of 0.3 g of nickel nitrate was dissolved in an aqueous solution and then 1.5 g of the above PA-Mo molybdenum carbide was added and stirred. This was then rotary evaporated at 50 °C and placed in a drying oven at 60 °C for 12 h and then carbonized in a tube furnace under nitrogen at a ramp rate of 5(°) / min to 800 °C and held for 3 h. The resulting black precipitate was filtered off and dried to obtain the Ni@Mo2C catalyst.

[0045] The reaction was performed using an electrochemical workstation, where nickel foam was used as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and atmospheric pressure, 100 mL of a sealed glass bottle was charged with 1 M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst into the reaction bottle, and 2% H2S gas (100 ml / min) was bubbled for 1 h. The electrocatalytic reaction was carried out at room temperature at a constant voltage of 2 V at a rate of 400 rpm for 8 h. The amount of hydrogen produced was detected by gas chromatography, with a yield of 88%. Then 2% H2S gas (100 ml / min) was continued to be bubbled for 1 h, repeated 3 times. The solution pH was adjusted to 2 to precipitate, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60 °C, and analyzed by P-XRD, with a sulfur yield of 81%.

[0046] Example 4:

[0047] Preparation of Ni@Mo2C catalyst: A solution of trimesic acid (1 g) in ethanol (50 mL) was slowly added to a solution of molybdic acid (1 g) in water (50 mL). A precipitate appeared upon mixing and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60 °C overnight. This is noted as HK-Mo. HK-Mo was placed in a porcelain boat and calcined at high temperature under nitrogen protection, with a heating rate of 5(°) / min to 800 °C and held for 3 h to obtain the PA-Mo molybdenum carbide catalyst. An amount of 0.3 g of nickel nitrate was dissolved in an aqueous solution, then 1.5 g of the above PA-Mo molybdenum carbide was added and stirred. After rotary evaporation at 50 °C, it was placed in a drying box at 60 °C for drying. After drying for 12 h, it was placed in a tube furnace for carbonization under nitrogen protection, with a heating rate of 5(°) / min to 800 °C and held for 3 h. The black precipitate obtained was filtered out and dried to obtain the Ni@Mo2C catalyst.

[0048] The reaction used an electrochemical workstation, in which nickel foam was used as the working electrode (WE) and carbon cloth as the counter electrode (CE). Under normal temperature and pressure, 100 mL of a sealed glass bottle was used, 1 M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst were added to the reaction bottle, and 2% H2S gas (100 ml / min) was introduced for 1 h. The electrocatalytic reaction was carried out at room temperature at a speed of 400 rpm under a constant voltage of 2 V for 8 h. The amount of hydrogen produced was detected by gas chromatography, and the yield was 65%. Then 2% H2S gas (100 ml / min) was continuously introduced for 1 h, and the process was repeated 3 times. The solution pH was adjusted to 2 to precipitate, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60 °C, and analyzed by P-XRD, obtaining a sulfur yield of 58%.

[0049] Example 5:

[0050] Preparation of Ni@Mo2C catalyst: A solution of trimesic acid (1 g) in ethanol (50 mL) was slowly added to a solution of molybdic acid (1 g) in water (50 mL). A precipitate appeared upon mixing and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60 °C overnight. This is noted as HK-Mo. HK-Mo was placed in a porcelain boat and calcined at high temperature under nitrogen protection, with a heating rate of 5(°) / min to 800 °C and held for 3 h to obtain the PA-Mo molybdenum carbide catalyst. An amount of 0.3 g of nickel nitrate was dissolved in an aqueous solution, then 1.5 g of the above PA-Mo molybdenum carbide was added and stirred. After rotary evaporation at 50 °C, it was placed in a drying box at 60 °C for drying. After drying for 12 h, it was placed in a tube furnace for carbonization under nitrogen protection, with a heating rate of 5(°) / min to 800 °C and held for 3 h. The black precipitate obtained was filtered out and dried to obtain the Ni@Mo2C catalyst.

[0051] The reaction was carried out using an electrochemical workstation, where nickel foam was used as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and atmospheric pressure, 100 mL of a sealed glass bottle was used, and 1 M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst were added to the reaction bottle, and 2% H2S gas (100 ml / min) was introduced for 1 h. The electrocatalytic reaction was carried out at room temperature at a speed of 400 rpm under a constant voltage of 2 V for 8 h. The amount of hydrogen produced was detected by gas chromatography, and the yield was 72%. Then 2% H2S gas (100 ml / min) was continuously introduced for 1 h, and the process was repeated 3 times. The solution pH was adjusted to 2 to precipitate, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60°C, and analyzed by P-XRD, with a sulfur yield of 65%.

[0052] Example 6:

[0053] Preparation of Ni@Mo2C catalyst: A solution of trimesic acid (1 g) in ethanol (50 mL) was slowly added to a solution of molybdic acid (2.5 g) in water (50 mL). After mixing, a precipitate appeared, and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60°C overnight. It was labeled HK-Mo. HK-Mo was placed in a porcelain boat and calcined at high temperature under nitrogen protection, with a temperature rise rate of 5(°) / min, to 800°C and held for 3 h, to obtain the PA-Mo molybdenum carbide catalyst. A certain amount of 0.1 g of nickel nitrate was dissolved in an aqueous solution, and then 1.5 g of the above PA-Mo molybdenum carbide was added and stirred. Then rotary evaporation was carried out at 50°C, and after rotary evaporation, it was placed in a drying box at 60°C for drying. After drying for 12 h, it was placed in a tube furnace and carbonized under nitrogen protection, with a temperature rise rate of 5(°) / min, to 800°C and held for 3 h. The black precipitate obtained was filtered and dried to obtain the Ni@Mo2C catalyst.

[0054] The reaction was carried out using an electrochemical workstation, where nickel foam was used as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and atmospheric pressure, 100 mL of a sealed glass bottle was used, and 1 M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst were added to the reaction bottle, and 2% H2S gas (100 ml / min) was introduced for 1 h. The electrocatalytic reaction was carried out at room temperature at a speed of 400 rpm under a constant voltage of 2 V for 8 h. The amount of hydrogen produced was detected by gas chromatography, and the yield was 72%. Then 2% H2S gas (100 ml / min) was continuously introduced for 1 h, and the process was repeated 3 times. The solution pH was adjusted to 2 to precipitate, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60°C, and analyzed by P-XRD, with a sulfur yield of 65%.

[0055] Example 7:

[0056] Preparation of Ni@Mo2C catalyst: A solution of trimesic acid (1 g) in ethanol (50 mL) was slowly added to a solution of molybdic acid (2.5 g) in water (50 mL). A precipitate appeared upon mixing and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60 °C overnight. This is denoted as HK-Mo. HK-Mo was placed in a porcelain boat and calcined under nitrogen at a ramp rate of 5(°) / min to 800 °C and held for 3 h to obtain the PA-Mo molybdenum carbide catalyst. An amount of 0.5 g of nickel nitrate was dissolved in an aqueous solution and then 1.5 g of the above PA-Mo molybdenum carbide was added and stirred. This was then rotary evaporated at 50 °C and left to dry in a drying cabinet at 60 °C for 12 h before being carbonized in a tube furnace under nitrogen at a ramp rate of 5(°) / min to 800 °C and held for 3 h. The resulting black precipitate was filtered off and dried to obtain the Ni@Mo2C catalyst.

[0057] The reaction was performed using an electrochemical workstation with nickel foam as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and atmospheric pressure, 100 mL of a sealed glass bottle was charged with 1 M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst into the reaction bottle, and 2% H2S gas (100 ml / min) was bubbled for 1 h. The electrocatalytic reaction was carried out at room temperature at a constant voltage of 2 V at a rate of 400 rpm for 8 h. The amount of hydrogen produced was detected by gas chromatography, with a yield of 86%. Then 2% H2S gas (100 ml / min) was continued to be bubbled for 1 h, repeated 3 times. The solution pH was adjusted to 2 to precipitate, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60 °C, and analyzed by P-XRD, with a sulfur yield of 79%.

[0058] Example 8:

[0059] Preparation of the Ni@Mo2C catalyst: A solution of 1 g of mesitylene tribenzoic acid in 50 mL of ethanol was slowly added to a solution of 2.5 g of molybdic acid in 50 mL of water. A precipitate formed after mixing, and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60°C overnight. This was designated HK-Mo. HK-Mo was placed in a porcelain boat and calcined under nitrogen at a heating rate of 5°C / min to 800°C and held for 3 h, yielding the PA-Mo molybdenum carbide catalyst. A certain amount of 1 g of nickel nitrate was dissolved in the aqueous solution, followed by the addition of 1.5 g of the PA-Mo molybdenum carbide and stirring. The mixture was then rotary evaporated at 50°C and dried in a desiccator at 60°C for 12 h. After drying, the mixture was carbonized in a tube furnace under nitrogen at a heating rate of 5°C / min to 800°C and held for 3 h. The resulting black precipitate was filtered and dried to yield the Ni@Mo2C catalyst.

[0060] The reaction was performed using an electrochemical workstation with nickel foam as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and pressure, a 100-mL sealed glass bottle was charged with 1M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst. 2% H2S gas (100 mL / min) was introduced for 1 hour. The electrocatalytic reaction was carried out at room temperature at a rate of 400 rpm and a constant voltage of 2 V for 8 hours. The hydrogen production was measured by gas chromatography, yielding 80%. 2% H2S gas (100 mL / min) was then introduced for 1 hour, repeated three times. The solution pH was adjusted to 2, resulting in precipitation. The solution was then stored in an ice bath for 12 hours. The pale yellow sulfur precipitate was then collected, washed with water and ethanol, dried at 60°C, and analyzed by P-XRD, yielding a sulfur yield of 73%.

[0061] Example 9:

[0062] Preparation of the Ni@Mo2C catalyst: A solution of 1 g of mesitylene tribenzoic acid in 50 mL of ethanol was slowly added to a solution of 2.5 g of molybdic acid in 50 mL of water. A precipitate formed after mixing, and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60°C overnight. This was designated HK-Mo. HK-Mo was placed in a porcelain boat and calcined under nitrogen at a heating rate of 5°C / min to 800°C and held for 3 h, yielding the PA-Mo molybdenum carbide catalyst. 0.3 g of nickel nitrate was dissolved in aqueous solution, followed by the addition of 1.5 g of the PA-Mo molybdenum carbide and stirring. The mixture was then rotary evaporated at 50°C and dried in a desiccator at 60°C for 12 h. After drying, the mixture was carbonized in a tube furnace under nitrogen at a heating rate of 5°C / min to 800°C and held for 3 h. The resulting black precipitate was filtered and dried to yield the Ni@Mo2C catalyst.

[0063] The reaction was carried out using an electrochemical workstation, where nickel foam was used as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and atmospheric pressure, 100 mL of a sealed glass bottle was charged with 1 M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst into the reaction bottle, and 2% H2S gas (100 ml / min) was passed for 1 h. The electrocatalytic reaction was carried out at room temperature at a rate of 400 rpm under a constant voltage of 2 V for 8 h. The amount of hydrogen produced was detected by gas chromatography, and the yield was 99%. Then 2% H2S gas (100 ml / min) was continuously passed for 1 h, repeated 3 times. The solution pH was adjusted to 1 to precipitate, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60°C, and analyzed by P-XRD, giving a sulfur yield of 90%.

[0064] Example 10:

[0065] Preparation of Ni@Mo2C catalyst: A solution of trimesic acid (1 g) in ethanol (50 mL) was slowly added to a solution of molybdic acid (2.5 g) in water (50 mL). After mixing, a precipitate appeared and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60°C overnight. Denoted as HK-Mo. HK-Mo was placed in a porcelain boat and calcined at high temperature under nitrogen protection conditions, with a temperature rise rate of 5(°) / min to 800°C and retention for 3 h, to obtain the PA-Mo molybdenum carbide catalyst. A certain amount of 0.3 g of nickel nitrate was dissolved in an aqueous solution, then 1.5 g of the above PA-Mo molybdenum carbide was added and stirred. Then rotary evaporation was carried out at 50°C, and after rotary evaporation, it was placed in a drying box at 60°C for drying. After drying for 12 h, it was placed in a tube furnace and carbonized under nitrogen protection conditions, with a temperature rise rate of 5(°) / min to 800°C and retention for 3 h. The black precipitate obtained was filtered out and dried to obtain the Ni@Mo2C catalyst.

[0066] The reaction was carried out using an electrochemical workstation, where nickel foam was used as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and atmospheric pressure, 100 mL of a sealed glass bottle was charged with 1 M NaOH solution (60 mL) and 40 mg of Ni@Mo2C catalyst into the reaction bottle, and 2% H2S gas (100 ml / min) was passed for 1 h. The electrocatalytic reaction was carried out at room temperature at a rate of 400 rpm under a constant voltage of 2 V for 8 h. The amount of hydrogen produced was detected by gas chromatography, and the yield was 99%. Then 2% H2S gas (100 ml / min) was continuously passed for 1 h, repeated 3 times. The solution pH was adjusted to 3 to precipitate, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60°C, and analyzed by P-XRD, giving a sulfur yield of 84%.

[0067] Comparative Example 1:

[0068] Preparation of Ni@Mo2C catalyst: A solution of trimesic acid (1 g) in ethanol (50 mL) was slowly added to a solution of molybdic acid (2.5 g) in water (50 mL). A precipitate appeared upon mixing and stirring was continued for 2 h. After washing with ethanol, the precipitate was dried at 60 °C overnight. This is denoted as HK-Mo. HK-Mo was placed in a porcelain boat and calcined at high temperature under nitrogen protection, with a heating rate of 5(°) / min to 800 °C and held for 3 h to obtain the PA-Mo molybdenum carbide catalyst.

[0069] The reaction was performed using an electrochemical workstation, with nickel foam as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and atmospheric pressure, 100 mL of a sealed glass bottle was charged with 1 M NaOH solution (60 mL) and 40 mg of PA-Mo catalyst into the reaction bottle, and 2% H2S gas (100 ml / min) was passed for 1 h. The electrocatalytic reaction was carried out at room temperature at a constant voltage of 2 V at a rate of 400 rpm for 8 h. The amount of hydrogen produced was detected by gas chromatography, with a yield of 51%. Then 2% H2S gas (100 ml / min) was continued to be passed for 1 h, repeated 3 times. The solution was precipitated by adjusting the pH to 2, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60 °C, and analyzed by P-XRD, with a sulfur yield of 43%.

[0070] Comparative Example 2:

[0071] The reaction was performed using an electrochemical workstation, with nickel foam as the working electrode (WE) and carbon cloth as the counter electrode (CE). At room temperature and atmospheric pressure, 100 mL of a sealed glass bottle was charged with 1 M NaOH solution (60 mL), and 2% H2S gas (100 ml / min) was passed for 1 h. Without adding catalyst, the electrocatalytic reaction was carried out at room temperature at a constant voltage of 2 V at a rate of 400 rpm for 8 h. The amount of hydrogen produced was detected by gas chromatography, with a yield of 30%. Then 2% H2S gas (100 ml / min) was continued to be passed for 1 h, repeated 3 times. The solution was precipitated by adjusting the pH to 2, and the solution was stored in an ice bath for 12 h, then the light yellow sulfur precipitate was collected, washed with water and ethanol, dried at 60 °C, and analyzed by P-XRD, with a sulfur yield of 24%.

Claims

1. A method for preparing a catalyst for indirect electrocatalytic decomposition of hydrogen sulfide and its application, characterized by: (1) preparing an indirect electrocatalyst; (2) introducing hydrogen sulfide into an electrolyte; (3) electrolyzing the electrolyte containing hydrogen sulfide; (4) filtering and recovering the catalyst; (5) adjusting the pH value of the solution and storing it in an ice bath to recover a light yellow sulfur precipitate; (6) washing the catalyst with water and ethanol to obtain a sulfur product.

2. The method according to claim 1, characterized in that A preparation method for a Ni@Mo2C catalyst comprises the following steps: slowly adding an ethanol solution of mesitylene tribenzoic acid to an H2O solution of molybdic acid, mixing to produce a precipitate, continuing stirring, filtering the precipitate, washing the precipitate with ethanol, and drying overnight, which is recorded as HK-Mo; placing the HK-Mo in a porcelain boat and calcining it at high temperature under nitrogen protection to obtain a PA-Mo molybdenum carbide catalyst; dissolving a certain amount of nickel nitrate in an aqueous solution, then adding the prepared PA-Mo molybdenum carbide and stirring for a certain time, then performing rotary evaporation on a rotary evaporator, drying the precipitate overnight, and then placing the product in a tubular furnace and calcining it under nitrogen protection to obtain a black precipitated Ni@Mo2C catalyst.

3. The method according to claim 1, wherein nickel foam is used as a working electrode (WE) and carbon cloth is used as a counter electrode (CE); a NaOH solution and a Ni@Mo2C catalyst are added to an electrolytic cell, and H2S gas is introduced into the electrolytic cell. Hydrogen and sulfur are electrolyzed at a certain voltage to produce hydrogen and sulfur. After the reaction is completed, the pH of the solution is adjusted to obtain sulfur.

4. The method according to claim 1, wherein In order to further separate sulfur, the dark yellow polysulfide solution is adjusted to a pH of 1 to 3 for precipitation. The solution is stored in an ice bath, and then the pale yellow sulfur precipitate that appears is collected to obtain a sulfur product.

5. The preparation method according to claim 2, characterized in that The mass ratio of the materials of styrene tribenzoic acid, molybdic acid and nickel nitrate is 0.5-2:1-5:0.1-1.

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